“A splendid time was guaranteed for all,” as Apple/Capitol unveiled a new 50th-anniversary remix of the Beatles’ landmark recording “Sgt. Pepper’s Lonely Hearts Club Band” to a small invited audience of journalists during a morning playback at Capitol’s Studio A and to fans at a sold-out evening Grammy Museum event on Tuesday.

Originally issued on June 1, 1967, the zeitgeist-defining, Grammy-winning bestseller will be celebrated May 26 in six-disc, two-CD, one-CD and double-LP packages; the six-disc version will include video components and a 5.1 surround mix. All configurations will feature the album as remixed by Giles Martin, son of the Beatles’ late producer Sir George Martin, and Sam Okell.

At the Capitol presentation, Martin – who worked with his father on Beatles projects beginning with “Anthology” (1995) and continuing with “The Beatles ‘Love’” (2006) – called the task of creating a new version of one of the most acclaimed and cherished recordings of all-time “humbling.”

Attempting to formulate a 21st-century mix of the record that served as the starting gun for the Summer of Love half a century ago, Martin and Okell employed as a road map the monophonic version of “Sgt. Pepper,” issued at the same time as the original stereo LP, which contains sometimes significantly different sonic treatments of the record’s songs. (The Beatles’ long-deleted mono albums were reissued in 2009.)

Band members John Lennon, Paul McCartney, George Harrison and Ringo Starr took hands-on roles in making mono mixes of the their albums and left the stereo mixes to Martin and his engineers, since stereo was still at the time, in Martin’s words, “a novelty.”

Some of the most dramatic differences on the mono version are preserved in the new stereo mix, most particularly on McCartney’s ballad “She’s Leaving Home.” Martin noted that in mono form, “It’s a whole semi-tone higher.” The higher pitch adds an additional tug to McCartney’s already poignant vocal.

For “Lucy in the Sky With Diamonds,” the mixing team further enhanced the manipulated sound of Lennon’s voice by deploying additional automatic double-tracking (ADT) to bolster the acid-drenched sound of the song. “His voice is far more screwed around with – I think the term is f—ed with,” Martin said.

Much of the astonishing definition of the new “Sgt. Pepper” is the result of the producers’ work with the earliest iterations of the master tapes, before they were “bounced down” heavily to overcome the limitations of the four-track board at EMI’s Abbey Road Studios. “We’re mixing off of generations of tape that we’ve never mixed off,” Martin noted.

The anniversary “Sgt. Pepper” packages will also include an “alternate” version of the album, as well as some extras that show the band grappling, sometimes unsuccessfully, with the ideal way to manifest their goals in the studio.

The most striking outtake played by Martin was a stab at a vocal “choir” rendition of the thunderous E chord, ultimately played on overdubbed pianos, that concludes “A Day in the Life.” Martin noted dryly, “It turned out to be not the best idea.”

The Capitol audience sat in rapt silence as a playback of the new stereo mix rolled. The Martin-Okell version sports the harder-rocking, assertive sound of the 1967 mono, with McCartney’s bass and Starr’s drums frequently emphasized and some guitar details pushed up.

Aficionados of the mono “Sgt. Pepper” will appreciate elements buried on the ’67 stereo LP that rise to the surface on the fresh mix – Lennon’s command of “leave it!” to close “Lovely Rita,” a denser collage of stampeding animals at the climax of “Good Morning,” a more dizzying pileup of circus calliopes to end “Being For the Benefit of Mr. Kite!”

The remix’s finest hour may come in Harrison’s lone contribution, “Within You Without You,” on which the track’s plethora of exotic Indian instruments – sitar, tambura, tabla, swarmandal, dilruba – are heard in a rich, hypnotic clarity absent in the original.

The Beatlemaniac faithful filled the Grammy Museum, home of an ongoing series of Beatles vinyl LP listening sessions, and gave Martin a sustained standing ovation at the conclusion of the remix playback.

Some veteran Fab Four observers in the house voiced their approval of the new Martin rendering.

“He kept the essence of the mono mix,” said Chris Carter, longtime host of “Breakfast with the Beatles,” an L.A. radio institution that will now air on the new Sirius XM Beatles channel. “You’ve got the highlights of the mono mix in stereo. It takes the album] to a whole other level.”

David Jenkins of the Wild Honey collective, which has mounted several live full-album stagings of Beatles works benefiting autism research, said, “What’s most impressive is it takes the power of the mono mix and widens it. It’s the best of both worlds.”

On stage, the droll and persistently self-deprecating Martin assessed his work by offering a quip from his producing partner Okell on first hearing the finished remix: “It’s less disappointing than I thought it might be.”